The company has prohibited developers from selling any personal
information garnered from customers on their health apps to
advertisers. This change in policy may allay fears around privacy
as Apple starts to move into the health data business. The
move is also expected to increase trust in HealthKit in the run
up to the release of iOS 8 in September.

Healthkit is a tool for developers that allows health and fitness
apps to work together to access customer's health data from the
Health app. It lets you pick and choose which pieces of your
health information you want to share.

Health's rules state that developers who build apps that tap into
Healthkit can collect the health data it holds. But now, even if
they do so, they cannot sell it to advertisers.